While chlorine dioxide gas is a gas that is safe to a living animal body at a low concentration (such as 0.1 ppm or less), it is known to have effects such as inactivation or deodorization against microorganisms such as bacteria, fungus, and virus even at such a low concentration.
A method for manufacturing chlorine dioxide by electrolyzing an electrolytic solution comprising a chlorite is known (Patent Literature 1). However, in the chlorine dioxide manufacturing method described in Patent Literature 1, there was a problem that since the pH of the electrolytic solution gradually increases when electrolysis is continuously performed, the electrolysis efficiency (production efficiency of chlorine dioxide) was reduced, and when an acid was added to reduce the pH, the storage stability of the electrolytic solution would be lost and the electrolytic solution will deteriorate over time. In order to solve this problem, a method for producing chlorine dioxide gas by performing electrolysis while maintaining the pH of the electrolytic solution during electrolysis at pH 4-8 has been proposed (Patent Literature 2).